Navigation system for a 3D virtual scene

ABSTRACT

A navigation system for navigating a three-dimensional (3D) scene that includes a model or object with which a user can interact. The system accommodates and helps both novice and advanced users. To do this, the system locks a cursor to a model point in a scene during panning and controls panning speed relative to a bounding box size of the scene.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to and claims priority to U.S. provisionalapplication entitled Steering Wheels having Ser. No. 60/975,366, byFitzmaurice, et al, filed Sep. 26, 2007 and incorporated by referenceherein. This application is also related to and claims priority to U.S.provisional application entitled Steering Wheels having Ser. No.61/022,640, by Fitzmaurice, et al, filed Jan. 22, 2008 and incorporatedby reference herein.

BACKGROUND

1. Field

The embodiments discussed herein are directed to a system that locks acursor to a model point in a scene during panning and controls panningspeed relative to a bounding box size of the.

2. Description of the Related Art

Today, operating with three dimensional (3D) scenes is becoming more andmore common. As a result, new or novice users are being confronted witha system that can be difficult and hard to use. However, it is alsonecessary to allow experienced users to also use the 3D systemseffectively. What is needed is a system that accommodates and helps bothnovice and advanced users.

SUMMARY

A navigation system for navigating a three-dimensional (3D) scene thatincludes a model or object with which a user can interact. The systemaccommodates and helps both novice and advanced users. To do this, thesystem locks a cursor to a model point in a scene during panning andcontrols panning speed relative to a bounding box size of the scene bydetecting activation of a mouse button, setting a pan rate of movementspeed responsive to a model in a scene and panning responsive to cursormotion using the speed.

These together with other aspects and advantages which will besubsequently apparent, reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing had to the accompanying drawings forming a part hereof, whereinlike numerals refer to like parts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates view object, tour and full navigation GUI wheels andthe corresponding mini or pie cursor GUIs.

FIG. 2 depicts a 2D wheel.

FIG. 2 a depicts other mini-wheels.

FIGS. 3 a and 3 b depict the hit zones of the wheels.

FIG. 4 shows cursor motion and wedge tool focus.

FIGS. 4 a and 4 b shows switching between big and mini wheels.

FIG. 5, including 5 a-5 d, shows pie cursor operation.

FIG. 6 shows enlarged hit zones for the pie cursor.

FIG. 7 shows cursors to various tools.

FIG. 8 shows cursor wrapping.

FIG. 9 shows tool tips.

FIG. 10 illustrates close too and open tool menu nibs.

FIGS. 11 a-11 d show first contact GUIs.

FIG. 12 shows a cursor when used in a model point zoom with the centertool.

FIGS. 13-15 show center point section and centering.

FIGS. 16-18 show the focus sphere characteristics.

FIG. 19 shows locations of a sphere relative to a model.

FIG. 20 shows an orientation ring.

FIGS. 21 and 22 show tool warnings.

FIGS. 23 a-23 c show rewind cursor appearance.

FIGS. 24 a-24 c show rewinding.

FIG. 25 shows a forward tool tip.

FIG. 26 shows a warning for an invalid action.

FIGS. 27 a and 27 b show a perspective slider.

FIG. 28 shows forward motion.

FIG. 29 a shows an up/down slider and 29 b shows up down motion.

FIGS. 30-32 show a walk.

FIG. 33 shows walk cursors.

FIG. 34 shows optional cursors for the mini wheel or pie cursor.

FIG. 35 shows tap activation operation.

FIG. 36 shows center operation.

FIG. 37 shows sphere operation.

FIG. 38 shows cursor wrapping operation.

FIG. 39 shows zoom operation.

FIGS. 40 and 41 show rewind operation while FIG. 40 a shows the historydata structure.

FIG. 42 shows forward operation.

FIG. 43 shows up/down operation.

FIG. 44 shows walk operation.

FIG. 45 shows pan operation.

FIG. 46 shows mini-wheel activation operation.

FIG. 47 shows parity maintenance between perspective and orthographicprojections.

FIG. 48 shows system hardware.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The embodiments of the present invention discussed herein provide anavigation system for three dimensional (3D) scene navigation for newand experienced users that allow fast and safe navigation within a 3Dscene (or 2D scene). The system, as depicted in FIG. 1, includes a set100 of graphical user interface (GUI) navigation widgets or wheels (ornavigation tools) and corresponding miniature or pie menu versions,action tools that can be activated with the widgets and accompanying GUInavigation aids (not shown in this figure). The tools allow the user toperform different operations within the scene, such as panning andzooming.

The set of widgets or wheels, as includes a view object wheel 110 wouldtypically be used by a novice or an inexperienced 3D user to navigatearound an object in a scene, such as a model of an automobile or a part.The view object wheel 110 includes a center action tool 112. The centertool 112 is located in the upper wedge of the view object wheel 110. Thecenter tool is designed to bring (through an automatic pan operation) aclicked point on a model part or other object to the center of thecanvas view. A tool 110 secondary purpose is to establish a referencepoint in 3D space for other tools on the wheel 110. The orbit tool 114allows a user to orbit around an object in a scene where the center ofthe orbit is the center reference point. The zoom tool 116 allows a userto zoom in toward or out away from the center point. The rewind tool 118allows the user to rewind back through way points that are automaticallysaved as the user navigates about a scene.

A tour wheel 120 would typically be used by a novice to navigate withina building. A full navigation wheel 130 is designed for an experienceduser and includes all of the tools of the object 110 and tour 120wheels. The tour wheel 120 includes the rewind tool discussed above. Thetour wheel 120 also includes a forward action tool 122. This forwardtool 122 allows a user to move forward in the scene toward an object ormodel in the scene. If there is no object beneath the cursor, no motionoccurs and the user is informed that no motion will occur via an invalidaction or prohibited action message. A look tool 124 allows a user to“look” or change the view toward the left, right, up or down much theway a person turns their head in these directions. An up/down tool 126allows the user to move vertically up and down within the scene.

The full navigation wheel 130 includes all of the tools functionality ofthe object 110 and tour 120 navigation tools with additional capability.A walk tool 132 allows users to interactively walk about in 3D space,moving forward and backwards and/or turning freely to the left or right.A pan tool 134 allows the user to move up, down, right and left in thescene. The zoom tool moves in and out from the current cursor positioninstead of the center point.

Each of the wheels 110, 120 and 130 has a corresponding miniature ormini wheel 142, 144 and 146, respectively, each of which includes thesame action tools arranged in a pie type shape with each action tooloccupying a pie wedge that corresponds to the general location of theaction tool in the full size version.

A 2D navigation wheel 150 can also be provided as depicted in FIG. 2 andincludes the zoom 152, pan 154 and rewind 156 tools.

FIG. 2 a depicts enlarged versions of different mini-wheels some ofwhich have places for additional functions.

The navigation tools or wheels have some common characteristics.

The wheels are all tracking menus. A tracking menu is a cluster ofgraphical buttons, as with traditional menus, the cursor (sometimesshaped like an arrow) can be moved within the menu to select andinteract with items. However, unlike traditional menus, when the cursorhits the edge of the menu, the menu moves to continue tracking thecursor. Thus the menu always stays under the cursor and close at hand.Each wheel is displayed on the “canvas” of the screen display for 2Ddrawing and 3D model views. As long as the tool is active the wheel'smenu surface will track and follow the mouse or input device cursor whenit hits the edge of the menu surface. No mouse button down is requiredto get the menu to follow along. If the mouse cursor leaves the canvasarea, the menu still follows the mouse off-canvas, and the navigationtool menu will re-display when the mouse cursor returns to the canvasand moves the menu along with it.

Each wheel is “pinned” to the mouse cursor when the left mouse button isheld and a child tool is selected. When a child tool is no longer inuse, the wheel re-appears under the mouse cursor on the canvas. Thecursor is displayed exactly on the tool where it clicked to start thetool usage. So, for example, when the zoom tool is released, the wheelis aligned under the cursor exactly as it was when the mouse button wasfirst pressed, while the cursor was on the zoom tool. This allows usersto quickly re-invoke the same tool if needed. If the mouse cursor is offthe canvas when the sub-tool is exited, the wheel continues to track thecursor. If the user moves the cursor back towards the canvas area thewheel is moved along until it becomes visible again.

Each of the wheels has the most used functions or action tools on anexterior and lesser used functions in the center. In addition, functionscan occupy different amounts or space consistent with the importance ofthat function. The wheels, both full and mini, can have different sizesfrom 256×256 pixels down to 16×16 pixels. At a size of 32×32 the arrowcursor is no longer visible. The wheels appear on top of the canvas andany objects that are in the canvas are still visible since the wheelscan be made semi-transparent. The wheels' level of opacity can be set ina range between 25% and 90% (i.e., mostly opaque). No matter what thetransparency setting, the navigate tool or wheel is completely hidden(invisible) while one of its child tools is in use. Each child tool willdetermine any on screen display that may be required for itself. Whenthe child tool is released, the wheel is redisplayed using the currenttransparency settings.

The area of each action tool is highlighted (including wedges in themini wheels) as the cursor moves over the tool to alert the user thatthe user is over that tool. The area of each tool corresponds to theactivation or hit zones, as depicted in FIGS. 3 a (big wheels) and 3 b(mini wheels), unless the area is enlarged or enhanced, as will bediscussed in more detail later. As a cursor is moved about on the menu,the cursor location is mapped to a corresponding location inrepresentation of the hit zones. If the cursor is in one of the zones,that tool is highlighted. If the left mouse button is clicked down oractivated while in a zone the tool corresponding to the zone isactivated and the function starts at the point of the cursors.

The highlighting and selection for a mini wheel is particularly depictedin FIGS. 4 and 5. With the mini wheel, a full size wheel is miniaturizedinto a cursor-size with a radial layout based on the particularcorresponding full size navigation tool selected and in effect becomes apie menu cursor. The cursor (arrow) is preferably hidden and, in effect,the mini wheel menu itself serves to show cursor location. When thehidden system cursor hits the edge of the mini wheel, the mini wheelfollows the system cursor However, depending on which direction themouse is moved, the command in that direction within the pie layout ishighlighted as depicted in FIG. 4. Preferably, command or tool wedgesare color-coded with one wedge active at all times and a small label isshown below the cursor to indicate the tool name as shown in FIG. 4.

A mouse down event activates a highlighted command and the mini wheelcursor is replaced by the appropriate tool cursor. A user can then dragto operate the command (for example, dragging to zoom in/out using thestandard zoom tool cursor). Releasing the mouse button brings back themini wheel cursor as depicted in FIGS. 4 a and 4 b. The selection andoperation of any of the commands in a mini wheel cursor is only onebutton press away and can be performed in-place The one button pressindicates both which command is being activated and the starting pointfor that command. By strategically planning ahead, a user is able toadjust their mouse input “approach path” to select a target object suchthat the desired command wedge is highlighted when over the targetobject. Thus, the desired command can immediately be activated with amouse down event. This effectively merges pointing and command selectioninto a single act.

FIG. 5, including 5 a-5 c, shows an example usage of pointing, commandselection and command operation for the mini wheel cursor. FIG. 5 ashows the cursor motion to highlight a command. FIG. 5 b shows clickingto activate the command (a pan tool). FIG. 5 c shows dragging to operatethe pan tool and FIG. 5 d shows the release of the mouse button todeselect the tool and restore the mini wheel cursor.

The wedge selection or tool associated with a mini wheel or pie cursorcan be enhanced by extending the hit zone of the active wedge as shownin FIG. 6. As depicted the wedge hit zone is expanded (dotted line) tobe larger than the visible tool wedge by a small percentage such as 10%.This allows for a subtle form of wedge stickiness and also serves toreduce the instability that can occur if the input point is at thecenter of the pie cursor. The hotspot for the pie cursor lies within theactive wedge and is the true cursor position. Since the wedges arefairly small, and the true cursor position is usually at the outer edgeof the wedge, the hotspot becomes very predictable. As previouslydiscussed, the pie cursor is not a pop-up menu; rather, like a regulartool, you select it from the toolbar and it becomes your cursor thuschanging your input mode.

Each wheel exhibits a slide under behavior when the ShowMotion UI and/orthe View Cube are displayed on the canvas. The wheel passes under bothof these other features' onscreen displays.

FIG. 7 depicts cursors that can be used when the look 702, pan 704,orbit 706, zoom 708, rewind 710 cursors are activated, as well as theprohibited operation/action cursor 712. Each of the cursors has textassociated with it when it is displayed above the canvas that providesthe name of the tool, such as the “Orbit Cursor” text shown for theorbit tool cursor 706.

As the above cursors are moved about on the canvas, when the cursorencounters the edge of the display or canvas, the cursor wraps around asdepicted in FIG. 8. As can be seen as the cursor moves from position 1to 2 to the left edge of the screen, the cursor reappears on the rightside of the screen at the same vertical position and traveling in thesame direction as shown by positions 3 and 4. When the cursor exits thetop or bottom, the cursor reenters at the same horizontal position.

All of the tools of each wheel can have a tool tip or descriptiongraphic (HUD—heads-up-display) that is displayed when the cursor hoversover the tool. FIG. 9 depicts a tool tip 902 for the pan tool 904 and atool tip 906 for the orbit tool 908. The tool tips are the same size foreach function. The HUD may also be shown below the cursor while a toolis in use. This HUD display element can follow the cursor about on thecanvas while the tool is active (left mouse down) and is removed whenthe user exits the tool (left mouse up). Some tools may offer morecomplicated displays or aids than just a description.

As depicted in FIG. 5, each full size wheel 1000 has a close button 1002that closes the GUI. The system stores and will remember the last toolthat was in use when one of the wheels is activated. When a wheel isclosed or dismissed, the previously active toolbar tool is restored ormade active. If no other tool has been activated in the session, the“Select Tool” menu will be activated by default when closing a wheel viathe close button. Each wheel also includes a menu button 1004. When themenu button 1004 is left mouse clicked, a menu is displayed. Right mouseclick anywhere on the wheel surface will also display this menu. As withstandard menus, hitting the ESC key will cancel the menu. The menu itemsfor the view and tour wheels can include:

Mini View Object Wheel Mini Tour Building Wheel Mini Full NavigationWheel ----------------------------- Full Navigation Wheel Basic Wheels-> View Object Wheel Tour Building Wheel ---------------------------- GoHome Fit to Window Restore Original Center ----------------------------[Application specific menu items, if any, go here]---------------------------- Help... Preferences...---------------------------- Close Wheel

The menu items for the full wheel can include:

Mini View Object Wheel Mini Tour Building Wheel Mini Full NavigationWheel ----------------------------- Full Navigation Wheel Basic Wheels-> View Object Wheel Tour Building Wheel ---------------------------- GoHome Fit to Window ---------------------------- Restore Original CenterLevel Camera Increase Walk Speed Decrease Walk Speed---------------------------- [Application specific menu items, if any,go here] ---------------------------- Help... Preferences...---------------------------- Close Wheel

When the 2D wheel is active it will display the following menu items inits menu:

Go Home Fit to Window ---------------------------- Help...Preferences... ---------------------------- Close Wheel

The first four menu items in the view, tour and full wheels switch tothe corresponding wheel, the “Basic Wheels” is a sub-menu with the twonovice wheels. Go Home moves the camera to the document's saved HomeView with a quick animation lasting 1 second. Fit to Window adjusts thecurrent camera to frame the 3D content to fit entirely within the view.Level Camera flattens the camera view rotation relative to the XY groundplane. Restore Original Center restores the view object wheel centerpoint to the center of the currently loaded model's bounding box.Increase/Decrease Walk Speed doubles or halves the current walk speed.Help brings up the help window for the wheels. Preferences brings up thePreference window for the wheels. Close Wheel exits from the currentwheel navigation tool and returns to the previous tool (or the defaulttool such as Select). Optional wheel menu arrangements can be provided.

To help users get started a set of graphic tool tips is provided thatincludes first contact tool tips depicted in FIGS. 11 a and 11 b forthose new to 3D navigation and those familiar with 3D navigation. FIG.11 a shows an initial graphic 1100 that includes tabs 1102 for noviceand advanced users. The tab for an advanced user is shown as selectedincludes a graphic 1104 of a full navigation wheel, the mini wheels anda tip 1106. The tip 1106 provides text on behavior 1108 (tracking andhide/show wheel) and wheel type selections 1110. The user can see eachselection type by positioning the cursor over a type. FIG. 11 billustrates a display of the full mini wheel type tip where all of thetools and their locations on the mini wheel are shown. In FIG. 11 b thefull navigation wheel tool tips has been selected for review and thelocations and of the actions/names of tools are noted. FIG. 11 cillustrates possible selections within the novice tab and once againtext describing behavior and possible selections are shown. FIG. 11 dshows a view object wheel tip having been selected where the operationsof the tools for that wheel are described in text. The typical use isshow by an image 1112 along side the other tool 1114.

When the system is first run and a 3D model is loaded into the canvaseither the view object wheel or the full navigation wheel is preferablybe displayed in the canvas or display in the lower left corner. Whiledisplayed in this manner the wheel is even more transparent than when itis active. The wheel is in an inactive or pinned state, and onlyresponds to mouse cursor rollover. While in this state the pinned wheeldoes not interact with any other tools or features. The pinned wheel hasno other functions. After the first run from installation, the currentlyselected wheel is pinned to the same location. (The wheel selection isstored as an option across sessions.) If a mini wheel is the currentlyselected wheel, then the full navigation wheel is displayed. When theuser moves the cursor into the pinned wheel's space a small combinedgraphical tooltip as discussed above and roll-over switch will pop up.As described above, the tool tip is broken up into different regionscorresponding to a wheel type. When the cursor rolls over one of thesetooltip regions, the pinned wheel changes to bring up the matchingwheel. When a mouse click is detected in the tool tip region or thewheel, the current wheel is activated (i.e., unpinned). The wheel is notto be pinned on startup again unless the user goes and re-enables thebehavior manually (“Always Show the Pinned Wheel on Startup” setting).If no click is detected the wheel stays pinned on cursor exit. If theuser does not click and moves the cursor beyond either the border of thewheel or tool tip, the tool tips go away and the wheel remains in thepinned state. Preferably, to get rid of the wheel users first activateit and then close the wheel, or select another tool. Otherwise the wheelremains pinned in the 3D canvas.

A main menu pull down menu can also be provided in an application toallow activation of one of the navigation tools, such as:

Mini View Object Wheel Mini Tour Building Wheel Mini Full NavigationWheel ----------------------------- Full Navigation Wheel Basic Wheels-> View Object Wheel Tour Building Wheel

Where the above-menu is ordered for an advanced user and could beinverted in order for a novice user.

As previously mentioned the center tool moves a clicked or designatedpoint on a model part to the center of the view and establishes a 3Dspace reference point. When the user places the cursor over the centerwedge and over a model part in the canvas or scene at the same time, thecursor will display as the select arrow 1202, as shown in FIG. 12. Whenthe user left mouse clicks to use the center tool, and starts to drag,the cursor icon changes to show the prohibited/invalid operation oraction cursor/symbol (see FIG. 7) as long as there is no model partdirectly under the cursor. A HUD message will also be displayed with thetext “Click or Drag over the model to set the Pivot.” When the cursor isover the model a center sphere, which will be discussed in more detailbelow, is displayed. The center sphere will not move with the cursor aslong as the cursor shows the prohibited symbol. When the cursor rolls ormoves over a model part the sphere jumps to that position and begins totrack the cursor, and the icon will change to the normal arrow icon. TheHUD message will then also go away. If the cursor is over the centerwedge but not over a model surface, the left mouse click will display amomentary HUD message until the mouse-up event occurs that has text asnoted above. If the Center Tool is active and the cursor is over a modelpart, then the system shows the center point sphere at the cursor'slocation in screen space projected onto the underlying model's surfaceas depicted in FIG. 13 (circled for ease of identification). Upon mouseup the view will be animated/panned to bring the current center point tothe center of the canvas or view as shown by the arrow in FIG. 14 wherethe “ghosting” is used to illustrate this movement. When the centerpoint reaches the center of the canvas the automatic view pan operationstops as shown in FIG. 15 and the center point sphere can be hidden. Thecenter point is stored for use with other tools on the view object wheelto use, namely zoom and orbit. While the center tool is active, agraphical tool description is shown below the cursor location on thecanvas with the following text: Center Tool.

The center point sphere represents a 3D point in model space. Asdiscussed above, this point is set by the center tool and used by theorbit and zoom tools that are found on the view object wheel. If theuser has not defined a center point by clicking in the canvas view, thenthe default center point location in space is preferably defined as thecenter of the currently loaded Model's bounding box. The sphere is a 3Dmodel that is placed into the current model view. Since the sphere is ageometric object with 3D geometry it may appear larger or smallerdepending on how far the target point is from the camera view, and itmay be occluded by any model geometry that falls between it and thecamera view.

Preferably, the center sphere is a “green ball” pivot indicator 1602preferably with a text label 1604. The sphere can have axis rings 1702around the perimeter as depicted in FIG. 17. The sphere should always bevisible and should be displayed completely solid when there is nointervening geometry, and be displayed as partially see through whenthere is occluding geometry between the camera and the sphere asdepicted in FIG. 18 where the sphere is shown with the label “Pivot”from the orbit tool. Note that as the two planes occlude the sphere thesphere becomes see through and remains visible. FIG. 18 shows a viewwith a corner of a cube pointing out of the page with the top 1802 ofthe sphere above the cube and the reminder of the sphere inside thecube. FIG. 19 illustrates a sphere completely outside a model (19 a),completely inside the model (19 b) and embedded in the model (19 c).

The sphere is preferably always accompanied by a text label where thelabel appears in a fixed pixel size on the canvas. The label ispreferably always drawn in front of any model geometry in the view. Thelabel text changes depending on which tool is using the center pointsphere. The label text when seen with the center tool is: CENTER

The view object wheel version of the orbit tool 114 (see FIG. 1) orcommand preferably always gets its pivot point from the center toolcenter sphere. It is preferably placed on the wheel at the bottom threequadrants. It also maintains a dominant up-axis of the scene or canvas.A left mouse click anywhere in the orbit wedge hit zone invokes theorbit tool. For the view object wheel the last defined center point(from the center tool) is used as the orbit operation's pivot point.Horizontal and vertical mouse movement rotates the view about this pivotpoint in the same way as the standard orbit tool does dragging thecursor on the canvas to the left orbits the camera view around the pivotpoint along the world Y axis and moves the camera to the left, the modelappears to turn to its right. Drag to the right does the opposite.Dragging the cursor upward orbits the camera around the pivot point onthe X axis relative to the screen and moves the camera downward.Dragging the cursor down does the opposite. While the mouse is held downand the orbit tool is active the cursor is changed to the orbit cursor706 (see FIG. 7). The cursor is allowed to wrap around the canvas whenthe Orbit tool is active. When the orbit tool is active the center pointsphere is preferably displayed in the canvas and the sphere's text labelis shown: CENTER. By default the system maintains the scene upright withrespect to the model. If this default is off, the orbit tool behaves inscreen space (not model space). When “Keep Scene Upright” is turned off,the orbit algorithm is changed to not force an explicit up direction.When “Keep Scene Upright” is off, a shift key modifier can be enabledthat, on mouse-down presents a graphical roll ring 2002 (see FIG. 20)HUD centered around the current pivot point, where up/down mouse motionadjusts the roll values for the camera. Note that the label for thegreen ball pivot point is turned off while the roll ring 2002 is up.When a user makes a selection using the orbit tool, the pivot or centerpoint is moved to the center of the bounding box of the currentselection. Subsequent orbit operations will use this pivot point unlessit is moved again by another selection or other navigation actions(e.g., Pan operation, etc.).

The zoom tool 116 (see FIG. 1) is invoked by clicking while in the hitzones for the tools on the wheels 110 and 130. The typical zoom-in andzoom-out operations preferably occur relative to the center point set bythe center tool. However, the zoom for the view object wheel has someconstraints placed on it that are not found in the version that isprovided for the full navigation wheel. The view version of zoom tool isconstrained in the following by the system so that it cannot zoom(dolly) in further than its focus point, it cannot zoom out farther thanthe minimum size constraint, and it can only zoom directly in to thecenter of the canvas, as it uses the target point set by the center toolas its focus. In the view object wheel the zoom tool is preferablyplaced in the top of the center two wedges just above the rewindcommand. The zoom tool has a graphical tooltip that includes the text:Zoom in or out from Center. Whenever the zoom tool is active, the targetpoint is indicated in the HUD by the green center point sphere with atext label: CENTER. When the camera is zooming, either automaticallyfrom a single click zoom, or interactively with the click and drag zoom,the zoom cursor previously discussed is shown along with the zoom customHUD with the text “Zoom Tool” below the cursor.

During operation, after a single left mouse click and release the cameraview will perform an animated transition and zoom in towards the currenttarget point. The amount the camera travels during this transition ispreferably defined as 25% of the distance from the camera view's currentlocation to the target point location. The zoom tool on the view objectwheel preferably always uses as its target point the last point createdby the center tool. This means that the view object wheel zoom toolpreferably always zooms directly to the center of the canvas. Zoom istypically a camera dolly operation; it typically does not change thecamera's field of view (FOV) in any way. Holding the Shift key whenclicking the zoom tool inverts the single click zoom, and moves thecamera view directly away from the target point. The zoom out distanceis preferably defined as 125% of the distance from the current cameraview location to the target point location.

Clicking on the zoom tool wedge will activate the zoom tool and alsoallow mouse dragging to zoom in our out from the current focus point.Again, the last defined center point is used as the target point for theview object wheel zoom tool. This means that this version of zoom alwayszooms in to the center of the canvas.

In the view object wheel, the zoom tool cannot zoom in forward beyondthe target point. The camera view will stop moving once it reaches theTarget Point and further mouse drag in that direction will have noeffect. The user can always reverse mouse drag direction to zoom backaway from the Target Point. When the user has reached this boundary anadditional message is displayed in the HUD: Change the Center point tozoom further

The zoom tool is also constrained when zooming out or away from thetarget point when using the view object wheel. The camera view cannot bemoved further away than a maximum distance, which is determined by themodel's bounds. Once the view has backed out to this maximum distancethe camera will stop and further mouse drag in that direction will haveno effect. User can always reverse their mouse drag direction to zoomback inward. A HUD message is provided as depicted in FIG. 21 with thisfigure indicating 2102 a maximum zoom-out has been reached. When theuser has reached this boundary an additional message can be displayed inthe HUD as depicted in FIG. 22. Also FIG. 22 shows that the HUD messageis readable on a variety of background colors since it is always drawnwith white text on a semi-transparent grey box.

The zoom tool can have additional modes available. When tool is activeand the user holds down the Shift key, a “+” cursor is shown and thesystem allows the user to perform a “zoom extents” operation. In thisoperation, clicking and dragging define a rectangle which is visuallyshown to the user, to define a zoomed view. Releasing the mouse afterthe clicking and dragging, zooms the view (using an animation) to matchthe defined rectangle as best as possible. At the end of the transition,the visual zoom rectangle fades away.

A cursor drag up or drag right will zoom the view in. A cursor drag leftor drag down mouse will zoom the view out. By default the directions forzoom-In are cursor drag up and right, but this can be inverted based onthe zoom direction options dialog setting.

The mouse scroll wheel can also be enabled for the view object wheel.Scrolling the wheel forward causes the view to zoom, and backwards tozoom out. Zooming with the scroll wheel is preferably always towards, oraway from, the center of the canvas. While scrolling with the wheel thetarget point sphere is displayed at the center of the canvas with thelabel discussed previously.

The rewind tool is found in all of the wheel interfaces. Its behaviordoes not change no matter which wheel it is found on. It is located in awheel differently depending on the wheel. The tool allows the user tonavigate 3D spaces with a level of security as they can always rewindback through their navigation history to a previous view location. Thetool presents this rewind history as a set of onscreen thumbnails thatshow each step the user has so far taken so far. The rewind tool alsolets users interactively drag between the waypoint thumbnails to runback and forth through their navigation history animating the cameraview as they do so. When the cursor is held over the rewind tool atooltip is shown below the wheel in the canvas with the text: Rewindthrough your movement history. The system uses “waypoints” to facilitatethe rewind function or command. Each waypoint is a captured camera viewposition+orientation, along with a thumbnail of the model as seen fromthe camera's current view at that location. As the user navigates using:the tools provided by the wheels (e.g., forward, orbit, center), or theViewCube available from AutoDesk (clicking or dragging) or any other 3Dscene navigation tool, these events are added to the navigation Rewindhistory. Every camera and viewport combination has a separate Rewindnavigation history queue. Thus, in a quad view (2×2 viewport)arrangement where there is a Front, Top, Right and Perspectivecamera/view, 4 separate Rewind queues are maintained. Each time themouse is released when using a navigation tool; the system stores thecurrent view as a new waypoint and appends it to a history list for thatcamera/view combination. This new waypoint is set as the “current”waypoint. In general, waypoints are preferably not captured or recorded(but can be) at stages during a tools usage, only at the ending viewposition when the tool interaction is completed. Some tools, such as thewalk tool described below, can generate multiple waypoints (see sectionbelow).

FIG. 23 a illustrates a cursor positioned over the rewind tool in theview navigation widget, when the user clicks on the tool, the widgetfades-out and the waypoint history fades-in as shown in FIGS. 23 b and23 c.

The rewind history list preferably works like an Undo/Redo mechanism,when the user rewinds and subsequently creates a new waypoint the newwaypoint becomes the end of the history list and all others after it intime are discarded. The rewind history is stored for the current modelonly. If a new section or model is loaded then the history is discarded.The rewind history also persists across wheel switching and all of thewheels can make use of it in the same manner. When another tool isselected and the wheels are dismissed, the rewind history continues tobe stored. When the user returns to navigation with the wheels byselecting them again, all previous history waypoints are retained andthe user can rewind through them normally. A maximum number of historyevents are saved (by default 100 events).

A single mouse click on the rewind wedge in the wheels 110, 120 and 130(see FIG. 1) will temporarily activate the rewind tool and display thehistory waypoint thumbnails as discussed above. Upon releasing the mousethe rewind history is backed up to the previous waypoint in the list.That previous waypoint is set as the “current” waypoint. The wheel isredisplayed and an animated camera transition is performed to transitionthe current view to the older waypoint's location and orientation. Therewind history thumbnail strip is displayed during the rewind animation.If no history has been created yet and the user clicks the rewind tool,the system displays an empty rewind thumbnail and does not change thecamera view in any way. The arrow cursor is hidden and the cursor forthe rewind tool, called the timeline or rewind cursor and composed offour corner brackets as shown in FIG. 24 a, is displayed while the mouseis held down. While the mouse is clicked or held down the rewind toolgraphical tool description element (HUD) is displayed below the cursoron the canvas with the text: Rewind Tool. Note that this HUD elementwill appear in front of the thumbnails.

If the user left mouse clicks and holds the mouse down, the rewind GUIas shown in FIG. 24 a is displayed. This GUI is a set of thumbnails 2402arranged in a row horizontally in the canvas over objects of the scene.The most recent or current history waypoint's thumbnail 2404 is showndirectly under the rewind cursor 2404 (angle lines around the thumbnail)and centered (vertical and horizontal) on the cursor position. Olderwaypoint thumbnails are shown to the left and will be clipped by thecanvas edge if there are too many to display. Newer waypoints are shownto the right and also may be clipped by the canvas edge. (Clippingsimply means these are HUD elements and will not be draw outside thecanvas bounds.)

If the user then drags the cursor to the right or left the currentwaypoint's border will start to fade out and the next (in the draggeddirection) thumbnail's border will begin to brighten as shown in FIG. 24b. The border is brightest when the cursor is dead center horizontallyon a given thumbnail.

The distance the cursor is currently placed between any two waypointthumbnails is used to control the transition of the camera view betweenthose two waypoint locations and orientations. So, if the cursor ishalfway between two waypoints, the camera view will be smoothly animatedto the halfway point between the two waypoint view locations usinglinear interpolation. The camera view is constantly updated to followthe transitions between these thumbnails and waypoints as the user dragsover them using the linear interpolation. This sequence of cursorposition changes and corresponding scene changes is shown in FIGS. 24a-24 c. Note that additional positional hints (instead or in combinationwith linear interpolation) may be used to more accurately reproduce themotion history. A noticeable snapping occurs when the cursor is draggednear the center of a thumbnail to allow a user to match exactly thesaved waypoint view.

When the user releases the mouse the camera will remain at its currentposition and orientation even if this is part way between two waypoints.

When the mouse is released: If the closest thumbnail under the cursor isnot the last in the history list (there are more thumbnails to the rightof it) or the cursor is not exactly on a saved waypoint, a new waypointthumbnail will be generated and info will be stored or updated. Thisselected waypoint becomes the “current waypoint” and any new waypointswill be created after it in the list. If there are any new waypointscreated, the entire list from this current one on will be discarded.

When the mouse is released if the closest waypoint under the cursor isthe last waypoint in the history list (no more thumbs to the right ofthe selected item) then the waypoint's information is replaced with thecamera's current position+orientation+thumbnail. This last waypointbecomes the current waypoint and any new views will be created after itin the list.

The rewind cursor is constrained to move only horizontally and graphical“corner borders” are also displayed surrounding the cursor to frame thecurrent thumbnail.

To access rewind history beyond what is currently visible in thethumbnail strip on the canvas, an automatic thumbnail strip scrollinghas been defined. When there are only two visible thumbnails remain inthe history due to canvas clipping, the rewind cursor remains fixed andthe thumbnail strip begins to move in the opposite direction of themouse movement. This movement is position-based not rate-controlled.

Rather than discard (or write over) all later in time waypoints when apast waypoint is selected, it is also possible to create a branch in therewind history and maintain all of the waypoints. Multiple waypoints canalso be compressed. As previously mentioned, waypoints are typicallysaved at the end of tool operation and at intervals within some tools.However, it is possible to constantly record waypoints in “highresolution” with small separations in time between them.

As previously discussed the tour building wheel 120 (see FIG. 1) isprimarily focused towards moving the camera (user) about in 3D buildingmodels or virtual spaces. It allows for forward movement, looking about,and moving between vertical floors. Along with the common close and menubuttons, this wheel provides four tool wedges: forward, up/down, lookand rewind. The rewind tool has been discussed above. Normally themiddle mouse scroll wheel (hardware) is allowed to zoom the view in orout. While the tour wheel is active the zoom behavior of the middlemouse scroll wheel is disabled to prevent the user from escaping theconstraints that are placed on 3D view navigation while using the tourwheel.

The forward tool or command is located at the top center of the tourbuilding wheel 122 (see FIG. 1) occupying the top three quadrants of theouter ring and is the primary method for moving the camera for the tourwheel. The tool tip text 2502 for this tool is: “Click to set target.Drag to adjust distance to the target.” as shown in FIG. 25

The forward tool moves the view towards a clicked focus point location.When the mouse is clicked over a model surface with the forward tool, afocus point is defined by projecting the cursor location on the canvasonto the model surface using ray casting in a “click-through” typemanner. If no model part falls under the cursor then camera view willnot move forward and a prohibited operation cursor 2602 (see also 710 ofFIG. 7) is temporarily displayed as shown in FIG. 26. If a model isfound then the focus point is set, and the camera is animated moving(zooming) in towards the target point when the mouse is released. Thetotal distance of this move is preferably half of the distance from thecurrent view plane to the focus point. While animating the view forward,the wheel and the cursor are preferably hidden.

The center point sphere is reused as the target point and the sphereremains displayed until the user releases the mouse. For this tool thesphere has no label. Instead an endpoint 2702 of a perspective slider(HUD) 2704 reads: Surface—as depicted in FIG. 27 a. A mark 2706 is shownat the very bottom of the scale indicating the starting camera position.This marker is labeled with text: START. The distance indicator 2708 isdisplayed during the click to go forward camera transition. A distancemarker 2708 moves along automatically with the camera motion. FIG. 27 bshows the wiper or marker 2708 between the start position and thesurface. The wiper changes size based on the drag distance (i.e., depthinto the scene). This element is shown while dragging to set distance(also while the view is animating with the click to go forward behaviorabove.) This display element is placed into the view just below thecursor on the canvas. When the transition is complete and the camerastops moving, the distance indicator HUD is hidden. This graphicaldisplay gives feedback on the distance moved from the camera view'sstarting position towards the focus point. An optional set of dottedlines or pass through markers are shown above and below the targetmarker, these indicate that the user may go forward beyond the target(surface), or that they may back up past the start.

Clicking and dragging on the forward tool wedge also sets the focuspoint in the same manner as for the click to go forward behaviordescribed previously, but instead of animating the camera towards thetarget automatically, the user may drag the mouse to move the viewforward (and back) to set the distance to the focus point interactively.

Like with a zoom tool the user may perform both the forward and backwardmovement with a single mouse drag action. This is basically a zoominteraction but the zoom amount is capped in both directions. Whileinteractively dragging the view with the forward tool, the tour buildingwheel is hidden. Dragging the mouse/cursor upward moves the viewforward. Dragging the cursor downward does the opposite.

The zoom forward distance is capped so that when the user has moved(dragged) forward right up to the focus point position, the tool resistsfurther mouse drag beyond that point in a resistance zone, which is apercentage of the distance to the surface, such as 95%. If the usercontinues to drag the mouse in the forward direction for a period oftime, they will be allowed to “pop-through” the view to beyond theexisting focus point position and continue to zoom in/move forward fromthere. This behavior allows users to push through solid surfaces orwalls.

The user may also interactively move backwards from their startingposition towards an invisible focus point that is behind the cameraview. A “sticky point” or range of no movement is defined for the startposition of the forward tool. To go backwards, the user must drag somedistance downward to move off the sticky point. Similar to the forwardmovement, a ray is cast behind the camera view plane to try and see howfar the user can move without entering a wall or passing through a modelsurface. If a surface is found, the camera is allowed to only movebackwards as far as ½ the distance from the start position to thesurface found behind the camera. Unlike forward the user cannot pushbeyond the surface that is detected behind the camera.) If no backwardsurface is found during the initial ray cast, the camera is allowed tomove backwards a small amount (roughly 25% of a forward ray). Again thecursor is hidden during this behavior.

During use, a user places cursor over target and clicks on the forwardtool wedge. At this point, as depicted in FIG. 28, a number thingshappen: the distance indicator HUD is shown just below the cursor's lastlocation, the current position indicator is placed at the start positionon the bottom of the vertical scale, the focus point sphere is shown inthe model view and the arrow cursor goes away (see image 1 of FIG. 28).In this example, the user has clicked on the wall to the right of thefireplace. Next, the user can now drag the mouse to move forward (image2), while doing so the camera is animated forward (zoom in) and thecurrent position indicator or marker (having a color such as orange)moves up along the scale towards the “Surface” marker. (Note that theuser can also drag to move backwards (zoom out) see details above.) Whenthe user drags forward far enough to reach the focus point the forwardview movement stops. The current position indicator aligns with thesurface marker (image 3). If the user keeps moving forward, the movementresumes and they are allowed to pass beyond the surface and continueforward. The current position indicator continues to move upward pastthe surface marker. The focus point sphere will become more and moretransparent as the camera view gets closer to it until it finallydisappears and the camera view passes through it allowing the user topass through the surface or wall (image 4).

The up/down tool 126 (see FIG. 1) is located in the bottom center wedgeof the tour wheel and in the bottom right quadrant of the fullnavigation tool (130). The up/down tool gives users a way to move theirview vertically between floors or levels of a building using an upvector in the model. Note that this is different than what is possiblewith the pan tool. Panning is dependent on the camera orientation. Forexample, if you are looking down at your feet (mostly looking at thefloor) and then try to pan up to get to the next floor above you, thiswould take a long time and significantly displace you since you aresliding along the camera plane (screen space) which, when looking down,is at an angle with respect to the floor planes. The up/down tool slidesalong a Y-up axis of the scene without displacing the user along thehorizontal plane of the view.

When the cursor is over the up/down tool on the wheel the tool tip textis: Move up or down.

A bounding box of the model (plus a small amount of extra padding10-15%) is used to determine an absolute high and low Y axis values. Theup/down tool is constrained by these values and cannot push the viewbeyond them in either direction.

To avoid sudden jumps in the camera view when the up/down tool isinvoked the following rules apply. If the camera is already above thebounding box high mark when the user first clicks and drags the mouse,then the system uses the current camera position as the high mark. Ifthe camera is already below the bounding box low mark when the userfirst clicks and drags the mouse, then the system uses the currentcamera position as the low mark.

When the up/down tool is active the display (see FIG. 29 a) shows aslider or scale 2902 that is similar to that of the forward tooldisplay. This HUD is displayed centered vertically at the cursor's lastposition on the canvas, and vertically with the current positionIndicator aligned the cursor's last location. The top 2904 of the scaleis marked to show the highest point that the camera or view can be movedto with this tool. This point on the scale has a label: Top. The bottom2906 of the scale is marked to show the lowest point that the camera canbe moved to with this tool. This point on the scale has a label: Bottom.An indicator marker 2908 (preferably orange in color) shows the currentcamera view position relative to the High and Low positions. When theuser moves the view up or down a slightly dimmer orange marker or shadowindicator 2910 is left in place to show the starting view position onthe scale.

During use of the up/down tool, a vertical mouse/cursor drag upward(relative to the view) will push the view up towards the high or topmarker. A mouse drag downward does the opposite. FIG. 29 b shows an upand down motion. The drag amount of the mouse can vary the up/downcamera direction directly or alternatively can move using a rate controldesign; this allows for small initial incremental camera movements andwith more cursor dragging larger camera movements.

The look tool on the tour wheel has movement keyboard keys disabledwhereas on the full navigation wheel, as discussed below they areenabled. The look tool 124 located in the top half of the middle circleon the tour building wheel 120 (see FIG. 1) and on the lower leftquadrant of the inner circle of the full navigation tool 130 as will bediscussed later herein. The tool tip when the cursor hovers over thistool reads: Look around your current position.

To look left or right, a horizontal drag or X-axis mouse movement(relative to the view) causes the view to rotate to the left or right.To look up or down, a vertical drag or Y-axis mouse movement causes theview to rotate up or down. The up and down looking is optionallyconstrained so that the view never flips upside down. The camera or viewcan be rotated until it looks nearly straight up or down in the tourwheel, but not beyond. When the Look tool is active the cursor ischanged to the look cursor 702 as shown in FIG. 7. The cursor is allowedto wrap around the canvas when the look tool is active.

While the mouse is held down the look tool graphical tool descriptionelement is displayed below the cursor on the canvas with the text: LookTool.

As previously discussed, the full navigation wheel 130 (see FIG. 1)contains eight tools: walk, up/down, look, center, orbit, zoom, rewindand pan.

The walk tool 132 allows users to interactively walk about in 3D space,moving forward and backwards and/or turning freely to the left or right.The walk is preferably along a horizontal axis or plane of the scene.The walk tool also allows shortcut key access to the up/down tool toadjust the view up or down while walking. The walk tool is preferablylocated in the top right interior wedge on the full navigation wheel.The tool tip text is: Click and drag in the direction you want to walk.

Clicking the left mouse button with the cursor over the walk toolactivates the walk tool. When the mouse is first clicked on the walktool the cursor changes to a default walk icon or cursor 3002 asdepicted in FIG. 30. If the user moves the mouse even a tiny bit whileholding the button down, the cursor is warped or moved to the center ofthe canvas (see arrow showing motion in FIG. 31), and a target circle orregion or motionless zone 3102 is displayed. This actual position forthis GUI display element (zone) is centered horizontally left to rightand adjacent to the bottom about ⅓ up from the bottom of the canvasvertically. If the user further drags the cursor in any direction awayfrom the center target 3102, then the camera view begins to move or“walk”.

The direction of the cursor from the center target or zone 3102determines the walk direction. Up is forward, down is backwards, left isturn left, right is turn right, and diagonal combines the two closestheadings. The distance of the cursor from the center target 3102determines the speed of walking. The closer to the center is slower,farther away is faster. A default speed is set based on scene spaceparameters, such as the size of the bounding box, and can be changed bythe user. Placing the cursor over the center circle area 3102 will stopcamera or view movement. At any time the user may release the mousebutton to end walking and redisplay the wheel.

While walking the cursor is changed to an arrow (a direction indicationcursor) 3202 that indicates the current move direction and rotation. InFIG. 32 the diagonal arrow cursor 3202 indicates that the user is movingforward and turning to the left.

There is a default cursor 3302 for when the camera is not moving and thecursor is hovering inside the center circle or zone as shown on the farleft of FIG. 33. There are eight walk direction cursors for when thecursor leaves the center circle HUD area as also shown in FIG. 25. Theseinclude forward 3304 and backward 3306, left 3308 and right 3310, andthe four diagonals 3312, 3314, 3316, 3318 between the primarydirections.

While the walk tool is active the following text is displayed as a HUDelement on the canvas: Hold down Shift key to move up or down. This HUDtext does not follow the cursor movement, and is instead fixed to thelower center of the canvas area.

While the walk tool is active the user may press and hold a hot key suchas the Shift key at any time to temporarily activate the Up/Down tooland move up or down. The walk tool is suspended while the Shift key isheld and the up/down tool is active and operates as previouslydiscussed. When Shift is pressed the cursor location (and therefore thewalking speed and heading) are temporarily stored. When the shift key isreleased the cursor is placed back to its previous location and the walkoperation continues on from where it left off. A walk tool option allowsusers to adjust the walking movement direction based on their currentcamera looking direction instead of the default ground plane. Thus, itcan be used in combination with the look tool to move around in 3Dspace.

It is possible and likely that users will activate the walk tool forlong periods of time (30 seconds to a minute, etc). In order to capturesome of these long walk events, the system defines multiple rewindevents during a single mouse drag walk event. Preferably, this is theonly tool that allows for multiple rewind events to be defined. Bydefault, a walk rewind event is preferably recorded every 5 seconds.Consequently, a thumbnail is added to the rewind thumbnail strip(history) for each event. If it is not possible to create thumbnailsduring a walk (due to performance issues or if it is too noticeableduring the walk), it may be possible to create the thumbnails on themouseUp event or, a less favorable solution, to use the same thumbnailfor all multiple walk events belonging to a given long walk draghistory. To increase walk speed (increase movement rate) the userpresses CTRL+Shift+>. To decrease walk speed (decrease movement rate)the user presses CTRL+Shift+<. Alternative hotkeys may be used.

The look tool 136 on the full navigation wheel 130 allows the user tomove the view while looking by pressing the arrow keys on the keyboard.The tool is located on the bottom left interior wedge on the fullnavigation wheel 130 (see FIG. 1). The tool tip text is: “Look aroundyour current position. Press arrow keys to move.” To look left or right,an horizontal drag or X-axis mouse movement in the view causes the viewto rotate to the left or right and to look up or down, vertical drag orY-axis mouse movement causes the view to rotate up or down (drag leftallows you to look left; drag up to look up; etc.). This up and downlooking in the full navigation tool is not constrained so that the viewcan flip upside down. The camera can be rotated continuously until theview somersaults.

The look tool can also have an additional mode. When the user holds downthe Shift key while the tool is active, the system performs a “look at”operation. Similar to the Center tool, the green ball is positioned andcan be dragged along the model surface. The surface beneath the greenball is highlighted. Once the key is released, the view animates to movethe green ball to the center of the view, roughly keeping the zoomfactor the same but orients the view to be looking “head-on” to thesurface where the green ball resides (e.g., the surface normal ispointing directly at the user/camera).

Shortcut key inputs from the keyboard are provided to extend the looktool for users using the full navigation tool who have keyboard access.These keys will cause the camera to move forward or backward, and leftor right. These movement commands are available while the look tool isactive. (left mouse down). The forward key command causes the camera orview to move forwards (dolly in) based on the camera's current heading.For example, if the user is looking straight up and presses this keythey will fly up into the air like superman. If they are lookingstraight ahead they will fly directly ahead. The camera movement ratefor the keys is determined by a walk speed factor that can be set by theuser. The move backwards key command causes the camera to move backwards(dolly out) based on the camera's current heading. The move left orsidestep left key command causes the camera to move to the left as ifthe user was panning horizontally. The move right or sidestep right keycommand causes the camera view to move to the right as if the user waspanning horizontally. No up or down movement key is provided.

Both the walk tool and the look tool take into consideration the scalesof the model space in which they are operating. The speed to movethrough an engine block is very different than what will work to movepast the Empire State Building. A base movement rate value isautomatically calculated, based on the model's bounding box when themodel is loaded. Both look and walk use the same base setting. Increaseor decrease speed commands can modify this base move rate setting to fitthe user's needs, and these ±modifications can be stored for theduration of the session.

When the look tool is active the cursor is changed to the look cursor702 as depicted in FIG. 7. The cursor is allowed to wrap around thecanvas while the look tool is active. While the mouse is held down thelook tool graphical tool description element is displayed below thecursor on the canvas with the text: Look Tool.

The orbit tool 114 appears on both the view object wheel 110 and thefull navigation wheel 130. The version on the full wheel uses the samemouse control scheme to orbit the view about a pivot point, but thistool has a more dynamically defined pivot point that is not alwaysdirectly in the center of the view. The tool is located on the left sidewedge of the full wheel 130 (see FIG. 1). As other tools are used on thefull navigation wheel, the pivot point location for the orbit tool isbeing constantly updated. By default the pivot is set to the center ofthe screen. The center point sphere 1602 (see FIG. 16) is preferablyused for the pivot point. The sphere remains displayed until the userreleases the mouse. For this tool the sphere label text is: PIVOT. Whilethe mouse is held down and the orbit tool is active the cursor ischanged to the orbit cursor 706 shown in FIG. 7. The cursor is allowedto wrap around the canvas while the orbit tool is active. While themouse is held down the orbit tool HUD element is displayed below thecursor on the canvas with the text: Orbit Tool.

If the user activates CTRL+Click or CTRL+Click and drags on a model inthe view with the orbit tool, a new pivot point is defined about whichto orbit. Subsequent orbits will use this pivot until the user defines anew one by using another tool, such as zoom, another CTRL+click on theorbit tool and navigating the view with another tool so that the pivotlocation ends up off screen.

By default the Keep Scene Upright option is on. If it is turned off,then the orbit tool behaves in screen space (not model space). When“Keep Scene Upright” is off, a Shift key modifier is enabled that, onmouse-down presents a graphical ring HUD (see FIG. 20 previouslydiscussed) centered around the current pivot point, where up/down orleft/right mouse motion adjusts the roll values for the camera. Thelabel for the green ball pivot point is turned off while the roll ringis up.

When a user makes a selection, the pivot point is moved to the center ofthe bounding box of the current selection. Subsequent orbit operationswill use this point unless it is moved again by another selection orother navigation actions (e.g., pan operation, etc.).

Pan operation of the full wheel is preferably a common pan operationexcept that the clicked point in the view will stay fixed to the cursorand not go flying off too fast or too slow.

For the full navigation wheel the tool is not constrained, and can zoomtowards or away from any point visible in the canvas. A single click tozoom in (left mouse button click and release) behaves like the singleclick behavior for the view wheel zoom tool, with the followingexceptions. The target point is set based on where the user placed theircursor over the model, not the center of the canvas. The user is allowedto click anywhere on the canvas to set the zoom target point and zoomwill zoom into this location. This behavior may be turned off. Thesingle click to zoom out (Shift+left mouse button click and release)zooms out away from the clicked point on the canvas. The target point isset based on where the user placed their cursor over the model, not thecenter of the canvas. The user is allowed to click on ‘nothing’ and canstill zoom. This Zoom tool also supports the invert mouse zoom optionsetting where the zoom can cause the scene to be inverted. Whenever thezoom tool is active on the full wheel, the target point is indicated asa green sphere with a text label and is the same HUD graphic as for theCenter tool shown earlier. The mouse scroll wheel will zoom in to thelast defined pivot/focus point in the same manner as the CTRL+Zoom shownabove.

The mini wheels (see FIG. 1) are designed for advanced users and provideeven more rapid access to the navigation action tools. Three Mini wheelsexist which are task-based: mini view object wheel 142, mini tourbuilding wheel 144 and mini full navigation wheel 146. The action toolswithin each mini wheel behave exactly like the big full wheel. Thegestural and spatial location are similar to the big full navigationwheel. For example, orbit is on the outer left wedge in the big fullwheel and the mini view object wheel. The mini wheels are preferablysmall (32×32 pixels) and replace the default “arrow” cursor. In thisdefault small mode, the arrow cursor is turned off. The mini wheels canbe made larger than the default 32×32 and in these cases, the arrowcursor is preferably made visible along with the active mini wheel. Themini view object wheel 142 contains the tools: zoom (top wedge), rewind,(right wedge), pan (bottom wedge), and orbit (left wedge). The mini tourbuilding wheel 144 contains the tools: walk (top wedge), rewind (rightwedge), up/down (bottom wedge), and look (left wedge). The mini fullnavigation wheel 146 contains the tools: zoom (top wedge), rewind (rightwedge), pan (bottom wedge), orbit (left wedge), center (top-left wedge),walk (top-right wedge), up/down (bottom-right wedge), and look(bottom-left wedge).

Showing the standard arrow cursor within a mini wheel or pie cursor canbe visually heavy and confusing. Preferably no cursor is shown and themini wheel visually acts as the cursor. However, there may be times whenit is useful to have a visible cursor. In such a situation, a smallerdot cursor (what can be called a flea cursor) can be provided asdepicted in FIG. 34 a or a miniaturized arrow cursor within the piecursor that indicates the precise mouse input and active hotspot canalso be provided as depicted in FIG. 34 b. A further alternative is tonot show the mini wheel cursor but display a modified arrow cursor asdepicted in FIG. 34 c. When the arrow cursor moves into a new commandwedge of an invisible pie cursor, the visible cursor is changed to thecorresponding tool cursor. Yet another approach is to use a click-holddesign during command activation within the pie cursor tolock-in/release a command/tool mode. A velocity based alternative canserve as a means of switching between command selection (high velocitymouse movement) and precision pointing (low velocity mouse movement). Toaccommodate precision pointing, the user can hit a modifier key such asthe Shift key which will lock-in the currently highlighted tool in themini-wheel and replace the mini-wheel with an arrow cursor. Holding theShift key will also retain the current tool for multiple mousemovements/clicks and allows the user to repeat a command multiple timesuntil the Shift key is released and the mini-wheel returns

All of the wheels can share a particular key as a shortcut key. Pressingthis shortcut can bring up the last used wheel for 3D, or just bring upthe 2D wheel for 2D content. Tapping the shortcut key when a wheel isalready up will bring the wheel down and activate the last tool (e.g.,Select Tool). The CTRL+Shift or another key can be used as a shortcutkey or hot key to activate/deactivate the wheels. Activating a wheelshould occur “transparently” from the current tool. For example, if thea first tool is active, a user can hit Ctrl+Shift to activate the viewobject wheel, navigate, hit Ctrl+Shift again to bring down the wheel andbe placed back into the first tool to continue working.

The flow of this shortcut key process 3500 is depicted in FIG. 35 andstarts with the user activating (pressing) and the system detecting thetrigger key 3502. The system then checks 3504 to determine whether thecorresponding tool is active and, if so, when the user releases 3506 thekey, the system checks 3508 to see whether the key was held down for atleast a threshold amount of time, such as _(—)1_ seconds. If held downfor the threshold time, the tool is kept 3510 active, otherwise it isdeactivated 3512. If the initial check 3504 indicates that the tool isnot active, it is activated 3514. When the user releases 3516 theactivation trigger, the system again checks 3518 the hold down timeagainst the threshold, deactivates 3520 the tool when not met and keeps3522 it active when met.

The center tool operation is depicted in FIG. 36 and starts with theuser pressing the mouse button which is detected 3602. The system thenchecks 3604 to see if the cursor is over the model by ray casting thecursor into the scene and determining whether the ray encountered themodel. If the cursor is over the model, the intersection point isdetermined 3606 and it is displayed 3608 on the model, preferably as thegreen ball. If the cursor is not over the model, the invalid operationmessage is displayed 3610. The system then determines 3612 whether themouse button has been released and, if so, again checks 3614 to see ifthe cursor is over the model. If so, the model is moved or animated 3616so that the intersection is in the center of the screen.

When the green ball or center sphere is used, it can be moved about inthe model space. As depicted in FIG. 37, when the user presses 3702 amouse button, the system checks 3704 to see if the cursor is over themodel. If so, like described above, the intersection point is determined3706 and the sphere is displayed 3708 at the intersection point of themodel. If not, the system checks 3710 as to whether the active toolallows the sphere to be anywhere in the model space. If so, the sphereis displayed 3712 at a specified depth into the model from the currentview position, such as the depth position from the last time it was onthe model. If the sphere is currently displayed 3714 on the model, thesphere is not moved 3716 and, if not, the sphere is not displayed 3718.The button status is then checked 3720 and if it is not down, the sphereis not displayed 3722.

The orbit operation, except as described above, has a conventional flowand so is not described herein.

For the tools that allow cursor wrapping, this operation, as depicted inFIG. 38 starts with the user moving 3802 the input device for moving thecursor and this being detected. When the cursor x position is greaterthan the window width 3804, the x position is set 3806 to zero. When thecursor x position is less than zero 3808, the x position is set 3810 tothe window width. When the cursor y position is greater than the windowheight 3812, the y position is set 3814 to zero. When the cursor yposition is less than zero 3816, the y position is set to the windowheight 3818. Once the cursor x and y values are adjusted, the cursor isdisplayed.

The zoom operation starts with the user initiating 3902 the zoom tool asdepicted in FIG. 39. The system checks 3904 to see if the mode is thezoom point mode. If not the existing pivot point (the sphere) isdisplayed 3906. If in the point mode, a check 3908 on whether the cursoris over the model is performed. If so, the point is determined 3910 anddisplayed 3912. If the cursor is not over the model, the intersectionpoint based on the alternate metric is displayed 3914, such as settingthe point a predetermined distance into the space from the currentcamera position or view point as previously described. When the usermoves 3914 the cursor, the camera or view is moved 3916 along the vector(in or out depending on the cursor motion) from the cursor to the pivotpoint. The motion of the camera is adjusted 3918 based on maximum limitsand whether the pivot point has been encountered. When the mouse buttonis released 3920, motion stops.

During tool operation, the rewind history is saved and this operation4002 is shown in FIG. 40. The system checks 4004 to see if this toolrequires intermediate waypoints and, if so, the elapsed time since thelast waypoint was saved is checked 4006 against the waypoint interval.If it is time to add a waypoint, the current view state information isadded 4008 to the rewind history and a thumbnail is created. When thetool does not require period waypoints, the system waits for the currenttool operation to end 4010 and then saves 4012 a new waypoint.

FIG. 40 a illustrates a linked list data structure used for the movementhistory where each entry 4020 includes view location, orientation, etc.

FIG. 41 shows the flow of the rewind tool operation. When the rewindtool is activated 4102, the hold down period of the tool is compared4104 to a threshold and if it is less than the threshold, the systemmoves or animates 4106 the view back one step (or back to the placewhere the last thumbnail was saved). When the user moves 4108 the rewindcursor 712 (see FIG. 7), the view is updated or animated 4110,preferably linearly based on the thumbnails involved in the motion ofthe rewind cursor as previously discussed. While the mouse button isdown 4112, the motion can continue.

During operation of the forward tool, when the user presses 4202 themouse button, the system determines 4204 whether the cursor is over themodel as depicted in FIG. 42 and if not the invalid operation cursor andmessage is displayed 4206. Otherwise, the intersection point isdetermined 4208 and displayed 4210 along with the motion scale (see FIG.27), followed by a move 4212 of the view a predetermined distance to theintersection point, such as preferably 50%. The scale is updated to showthe amount of movement. If the cursor is moved up 4214, the movementpercentage is increased 4216. If the cursor is moved down 4218, thepercentage is decreased 4220. When the mouse button is released 4222,the movement percentage is used to move both the view and the marker onthe perspective scale.

The up/down tool flow is activated 4302 and when the user moves 4304 thecursor, the camera view is moved 4306 along the up vector (a vectorvertical with respect to the model) based on the current position asshown in FIG. 43. The camera position is adjusted 4308 based on theminimum and maximum positions. The up/down scale is updated anddisplayed to show the move. This continues as long as the mouse buttonis down 4310.

As shown in FIG. 44, the walk tool, when activated 4402, the systemwarps 4404 the cursor to the starting position as previously discussed.When the cursor is inside the start region 4406, the speed is set 4408to zero. When the cursor is above the start region 4410, the view ismoved forward based on a speed that is increased 4412 responsive to thedistance the cursor is above the start region. When the cursor is belowthe start region 4414, the view is moved based on a speed that isdecreased 4416 responsive to the distance the cursor is below the startregion. When the cursor is to the right of the start region 4418, theview is rotated right 440 based on the distance the cursor is to theright of the start region. When the cursor is to the left of the startregion 4422, the view is rotated left 4424 based on the distance thecursor is to the left of the start region.

The pan operation (see FIG. 45), when activated 4502 by clicking throughthe pan tool, determines 4504 whether the cursor is over the model. Ifso, the intersection point is determined 4506 and a C:D ratio (the rateof movement speed) is set 4508 based on the distance to the intersectionpoint and the scene is panned based on the motion of the cursor usingthe ratio. If not over the cursor, the C:D ratio is set 4510 based on analternate metric, such as the dimensions or size of the model space andthe scene is panned responsive to cursor motion.

The mini-wheel activation (see FIG. 46), when activated 4602 by clickingthrough the pan tool, determines 4604 whether the cursor is within thewheel boundary. If not, the position of the wheel is updated 4606. Ifso, a determination 4608 is made as to whether the cursor is in thehighlighted wedge. If not, a determination is made 4610 as to whether itis within the specified distance of the wedge. If not, the wedge ishighlighted 4612.

Perspective and orthographic projections differ in that orthographicprojection has no sense of depth. Thus, when using only a view directionto determine the perspective and orthographic frustums for a scene, agreat disparity can emerge between the two after several cameraoperations have been carried out. Depicted in FIG. 47 is an approach4700 to maintaining parity between perspective and orthographicprojections, by using a single camera model, from which bothorthographic and perspective viewing frustums can be derived.

The standard pinhole perspective camera model has been augmented toinclude the distance to the geometry in the scene. This is updatedwhenever the camera position changes. That is, the user performs acamera move operation 4702, the camera parameters are updated 4704 andthe distance to the object is updated 4706. We then use this extrainformation to scale the orthographic frustum such that the size of thegeometry as it is viewed in orthographic projection mimics the size ofthe geometry as it is viewed in perspective projection. In doing this, adetermination 4708 is made as to whether the mode is projection orperspective. If perspective, the perspective frustum is calculated 4710.If orthographic, the distance is used to calculate 4712 the frustum.After the frustum is determined, the view is rendered 4714.

This distance value is used when calculating 4712 the orthographicfrustum; the parameters of orthographic width and height are calculatedfrom the pinhole camera model as follows:ORTHO_(w) =d×tan(f _(hor))ORTHO_(H) =d×tan(f _(ver))where d is the distance to the geometry in the scene, and f_(hor) andf_(ver) are the horizontal and vertical field-of-views, respectively.

The approximate distance to the object can be calculated based on thedistance of the perspective camera's eye to the center point. In doingthis the position of the center point is updated throughout all cameraoperations and generally lies on scene geometry. This is an effectiveand computationally inexpensive way of approximating distance to thegeometry in the scene. In addition, the magnitude of the view directionvector is transparent to the perspective projection model. However, asthis is an approximation, it does not work in all cases.

Another approach is to calculate the actual distance to the geometryview for every frame. While this ensures the calculation of theorthographic frustum is accurate, it is computationally expensive.Carrying out such calculations on a graphics processing unit (GPU) helpsreduce the load on a central processing unit (CPU) but can result inslower than real-time interaction for complex geometry.

The typical hardware 4800 for the system discussed herein, as depictedin FIG. 48, includes a display 4802 that can be a non sensitive displayor a sensitive display such as a touch or stylus type display screen asused in tablet or lap top type computers. The display is coupled to acomputer 4804 that can have the power of a cell phone, PDA, lap top,desk top or server type computer. A keyboard 4806 is provided for thekey based operations. A mouse 4608 or other cursor position controlinput device is used to control the cursors discussed herein. Adigitizing tablet 4810 that uses a stylus 4812 can also be coupled tothe computer. Other types on input devices that allow selection andcursor motion can also be used. The computer has associated memory andother types of storage capability (CD, hard disk, DVD, etc.) to allowthe programs or processes and data structures discussed herein to bestored. The system can operate over a network as the need arise for morepower or speed with the processes, etc. being distributed.

The embodiments of the present invention discussed provide a safe 3Dnavigation environment by clustering and caching tools; creating taskand skill-based tool sets; providing orientation awareness; enhancingtool feedback; providing pre-canned navigation; preventing errors; andrecovering from errors. Rapid access and use are provided by thetracking menu and click through features. The circular design of thewheels with important action tools on the exterior and less used toolsin the interior organizes the tools so they are easy to access in anorder that fits the tasks. The tool selection dialogs that allows newand advanced users to select a navigation tool makes the users quicklyaware of what is available and what are the navigation tool uses andallows immediate selection. The task grouping of commonly used tools forand limited to types of tasks helps prevent users from becoming confusedduring navigation. The customization of the action tools for the type oftask also prevents confusion and errors during navigation. The sphereprovides visual feedback to orient the users and the limitations onplacement of the sphere prevent navigation errors. The sliders providelocation feedback for dragging operations. Labels and icons reinforcethe operations of the tools being used. Constraints on navigation, suchas limiting motion to the bounding box or to a rear wall along withcursor control like the cursor screen wrapping, keeps users from gettinginto visually confusing states. Error recovery using rewind allows usersto return to a familiar visual state.

When any of the 3D wheels are selected, and the user then navigates to a2D sheet, the 2D navigation wheel can automatically become the selectedtool. When the 2D navigation tool is selected tool and the usernavigates to a 3D model, the last used 3D Wheel will become the selectedtool. If the ‘pinned’ option is enabled, show the 3D wheel pinned to thecanvas. If a non-compatible section type is displayed in the canvas thewheel(s) are dismissed and the Select Tool is activated instead.

Depending on the hotkey being used, it may be preferable to offerspring-loaded activation of the wheel. That is, only when the hotkey ispressed down, the wheel is visible and a user can interact with it. Oncethe hotkey is released, the wheel goes away. Again, this is an optionaloffering depending on the available hotkey and ease of articulation.

Alternative, and less ideal, systems may be built that offer thecollection and sets of navigation tools not using the Tracking Menudesign but instead using standard tools on a toolbar as well aspotentially offering hotkey access to the individual tools. So, forexample, a 3D navigation tool palette may offer: Forward, Look, Rewind,and Up/Down tools as one set and Center, Zoom, Rewind and Orbit asanother set.

Additionally, the shapes of the Tracking Menus may be altered (fromcircles to other shapes such as ovals or squares) and the tool regionsshapes may be reshaped and their proportions changed. The positioning ofthe tools may also be rearranged (e.g., the Orbit wedge on the left sideof the wheel could be moved to the top wedge).

Other elements such as the “green ball” may be different colors orshapes (e.g., square or pyramid or cross), orientation demarcations(e.g., tick marks instead of axis belts) and have different transparencydynamics.

Note also that the help text in the HUDs and tooltips change based onthe language settings of the computer (e.g., French, Chinese, etc).

The Rewind tool can have different visual representations for eachwaypoint and be presented to the user in different styles (such as aline with beads on it or timestamps, or a stack of thumbnails or a stackof graphical objects) and different orientations (e.g., vertical insteadof horizontal or in 3D). The Rewind mechanism can be attached todifferent input devices such as the mouse scrollwheel. Additionalinformation can be saved in the Rewind queue beyond camera position andorientation such as user settings, background color and styles,environment settings, rendering modes (e.g., line or shaded), cameraoptions such as orthographic or perspective projection, etc. WhenRewinding occurs, the previous state information is installed. In somecases, interpolation of application state information can occur betweentwo waypoints. For example, if the user switched between perspective andorthographic projection, these two projection modes would be blendedwhen rewinding between the two waypoint events.

In addition to the thumbnail strip, supplementary information can bepresented such as user or system annotations or indicating which toolswere active during the navigation history or other system activity. TheRewind thumbnail strip and graphics may be drawn semi-transparently.

Note for the Rewind Tool, it is possible to save the exact movement paththe user performed (instead of just the last position and orientationwhen the mouse is released). We call this “high resolution”. We havefound that this is mostly undesired and requires a lot of information tobe saved. However, we prototyped this and found it too frenzied whensomeone dragged through the rewind history. Nevertheless, it may beuseful in some applications in which a modifier key can be hit to togglebetween using low or high resolution rewind information.

Also navigation events may be created by the system (not explicitly bythe user). These can be added to the Rewind history.

Note that some events may be compressed or combined. For example,navigation events that occurred in which the view did not change or inwhich the view was composed of viewing empty space, are candidates forbeing dropped from the Rewind history or compressed into a single event.

The perspective sliders can be used in other contexts where for example3D depth information is useful to indicate. Note that an interestingproperty of the perspective slider is that it can take less visual spacethan a 2D slider since it is drawn in perspective.

The perspective slider does not have to relate to positional informationabout the 3D scene. For example, it can adjust volume settings. Thepoint is that it is drawn in perspective and the perspective may noteven match the current perspective in the 3D scene. Also, it could beused in a 2D canvas or 2D application.

The slider can be drawn such that it become more transparent as theslider is deeper in the scene. Thus, the “Start” end of the slider wouldbe more opaque and the “Surface” end would be more transparent.

The perspective slider can be drawn in many different visual ways usingdifferent metaphors such as a measurement ruler, or a road/driveway.

User or system annotation labels (text, graphics, iconic symbols) can beadded on or near the slider to provide information and context.

Additional semantic controls to go up one floor or down one floor—orother units (e.g. one meter, one foot, etc.), instead of up/down onepage or screen full of information on typical scrollbars.

Input snapping at interesting points along the slider (e.g., at eachfloor or tick mark indicating distance) may also be added for additionaluser control.

The up/down slider may also have additional graphics, annotations andtick marks on it to indicate application specific information orsizing/scale information. For example, tick marks may indicate floors ina building or where important elements are in a building (such as pipes,electrical junctions, etc. Drag snapping can occur at designated pointsalong the slider for precise movement. In some cases, it may be usefulto enable the tool without drawing the graphical slider. The slider mayalso be drawn semi-transparently. The preferred behavior is for theslider to initially appear near the current cursor position but it maybe useful to have it come up in other locations such as the center ofthe 3D canvas.

Pre and Post actions may be conducted while using the slider. Forexample, temporarily leveling the camera such that it is parallel to theground plane before and after actions are performed while using theUp/Down slider.

During mouse-dragging input for the Up/Down tool, the mouse movement canbe mapped to a non-linear function to move the camera. For example, anexponential function (which we use), has the property that initial mousemovement move the view in small amounts (for precise adjustments) and asthe drag motion gets longer, large view movements are generated. Thisdesign is handy if the user is viewing a condominium building and wantsto either move up/down in small distances (e.g., within a floor) orlarge distances (multiple floors at a time).

The Walk tool may deploy intelligent sensing to automatically determinea constant height above the current “ground plane” or horizontal surfacethe camera is currently over. Smoothing algorithms would make thetransition to different heights more visually pleasing. Additionalsensing could be used to avoid objects or walls. In addition note thatapplication specific or user customized HUD messages and graphicannotations can be triggered and displayed depending on the user'scurrent location, direction and speed of travel. Moreover to ensuresmooth traveling, the system may deploy “level of detail” adjustments inthe graphics rendering of the scene—drawing fewer polygons andperforming less rendering in dense scenes to approximate the visuals tokeep the refresh redrawing at a high rate. Hotkeys may be used toincrease or decrease the speed factor of the walk movement.

It is possible to have the walk left/right action and the up/down actionbe assigned to different parameters (e.g., navigation directions). Forexample, left/right may pan the user left/right instead of the defaultlook left/right. It is also possible to have the up/down mouse directionmap in the up/down direction instead of the in/out direction. Thus, arate-based pan operation which behaves directionally similar to thestandard Pan operation but is rate based.

As a convenience, if the user is walking using the Walk tool andperforms cursor-wrapping, moving the cursor into the dead zone willcause the movement to stop and reset the speed to zero. Thus, the userdoes not have to disengage the Walk tool (by releasing the mouse), or“unwrap” the cursor to pause and reset movement.

The method of cursor-wrapping can be activated while the user input isin the tracking state (e.g., moving a mouse device with no buttonspressed) or during a drag state (e.g. moving a mouse device with theleft mouse button pressed). In most scenarios, the cursor-wrapping isactive when a tool is active (such as dragging while orbiting).

With cursor-wrapping, the concepts are the same for a view displaying amixture of 2D and 3D or purely 2D content. When the cursor reaches theout-of-view position, an audio signal or visual signal can be displayednear the cursor location. For example, a chirp sound may be heard andthe cursor could fade out, then fade in on the other side.Alternatively, as an example, a small animation could be played showinga puff of smoke near the cursor location. Note that it is possible todisplay a portion of the cursor (and auxiliary graphics that arecurrently moving with the cursor—such as a tool/cursor label or statusinformation) at the out-of-view position and the remaining portion atthe new wrapped-around position. A number of variations are possible:clip the cursor and auxiliary graphics; re-format or reposition theauxiliary graphics to remain visible until the cursor completes itswrap; always keep the cursor displayed whole but allow auxiliarygraphics to be split.

The cursor-wrapping boundary may be dynamically defined to be not thecurrent view boundary but the boundary of the currently selected objector set of objects in the scene. In addition, the cursor-wrappingboundary could be dynamically determined to be the bounds of the objectit currently is over. Both of these cases are useful in that it keepsthe cursor near where the user is working and auxiliary information thatis moving with the cursor (such as dimensioning, status info, or stateinformation) can remain nearby

For the Tap Activation functionality, some embodiments will onlyimplement the quick tap toggle to activate/deactivate a tool and not thespring-loaded tap to activate a tool. In the quick tap situation, thetrigger will often require that “no mouse buttons are pressed” as thisis typically reserved for modifying the current selection.

If spring-loaded mode is supported, then mouse button presses areprocessed. However, the trigger key is already in use so if the toolrequires this key, it is unavailable. That is why we like less usedcombinations such as cntrl+shift or the Alt key. The First Contactpop-up mechanism is anchored to some visual element (e.g., a tool iconbutton in a toolbar or a widget in the 2D/3D scene). In our case we puta grayed-out 2D graphic on top of the 3D scene.

An important behavioral design to capture is that the FirstContactgraphic will dismiss itself when the user moves the cursor outside ofthe bounds of the graphic. Moving the cursor over sub-elements of thegraphic may change the graphic and switch default settings for the toolif the user chooses to activate the tool by clicking with the mouse.Thus, the user customizes the tool while learning about the tool orcollection of tools.

It is important to emphasize that the user can switch between options byclicking on sub-element graphics without activating the tool. Thesegraphics are used to select different sub-groups. We have found that animportant grouping is by user expertise. Moreover, users are very bad atself-assessment and classifying themselves as a novice or expert. Thus,we strategically do not use these terms and instead use terms such as“Familiar with 3D” and “New to 3D”.

One style of FirstContact is that the FirstContact graphics and toolchoosing should be seen only until the user activates the tool for thefirst time. This is to reduce information overload and clutter. The nexttime the user hovers over the anchor element, the FirstContact will notbe presented. This state information is preserved in the userpreferences and thus when the application is re-launched, FirstContactexposure is respected.

A mechanism exists to always re-activate FirstContact on applicationstart-up for those users who want this mechanism to persist and toalways be shown FirstContact.

The “green ball” navigation sphere has some important characteristics.The sphere becomes more transparent as the user gets closer during acamera movement operation (such as zoom) until the sphere is completelytransparent.

Also it is important to note that the size of the sphere resets afterany camera movement operation. When the sphere is interactively movedwithin the 3D scene, its size changes depending on the depth locationinformation. By default, the sphere does not cast a 3D shadow but itcould if desired. A texture could be added to the sphere to alter itsappearance.

We display the focus point sphere on tool activation (i.e., mouse down)and remove it on tool deactivation.

Alternatively, one may choose to show/hide the sphere when the tool isselected from the toolbar—in addition to when the tool is being used(e.g., while the mouse button is pressed). The sphere could change colorwhen the tool is being used (i.e., mouse down).

The sphere could change shape, color or be annotated with graphics oricons to indicate state or mode information. For example, within theOrbit tool, the sphere could indicate if dimensional constraints wereactive (e.g., only allowing orbit in x dimension).

In general modifier keys can be used for all of the tools to addadditional functionality.

The many features and advantages of the embodiments are apparent fromthe detailed specification and, thus, it is intended by the appendedclaims to cover all such features and advantages of the embodiments thatfall within the true spirit and scope thereof. Further, since numerousmodifications and changes will readily occur to those skilled in theart, it is not desired to limit the inventive embodiments to the exactconstruction and operation illustrated and described, and accordinglyall suitable modifications and equivalents may be resorted to, fallingwithin the scope thereof.

1. A method, comprising: detecting activation of a trigger; setting apan rate of movement speed based on location of the trigger relative toa model in a three-dimensional scene; and panning responsive to cursormotion using the speed, wherein the setting the pan rate comprises:determining an intersection point of a cursor with the model, and fixingthe intersection point in a view of the scene to the cursor as thecursor is moved.
 2. A method of panning in a three dimensional scene,comprising: determining whether a cursor is over a model in the scenewhen a pan operation is activated; setting a pan rate of movement speedto a value relative to a model metric when the cursor is not over themodel; determining an intersection point of the cursor on the model whenthe cursor is over the model; determining a distance of a view of thescene from the intersection point; setting the speed responsive to thedistance; and panning responsive to cursor motion using the speed, andwhere the intersection point is fixed in a view of the scene to thecursor as the cursor is moved.
 3. An apparatus, comprising: a display;and a computer detecting activation of a mouse button, setting a panrate of movement speed based on location of the trigger relative to amodel in a scene on the display and panning contents of the displayresponsive to cursor motion using the speed, and where the setting ofthe pan rate includes determining an intersection point of a cursor withthe model and fixing the intersection point in a view of the scene tothe cursor as the cursor is moved.
 4. A computer communicating with astorage having a program to cause a computer to execute an operation,comprising: detecting activation of a mouse button; setting a pan rateof movement speed based on location of the trigger relative to a modelin a scene; and panning responsive to cursor motion using the speed, andwhere the setting of the pan rate includes determining an intersectionpoint of a cursor with the model and fixing the intersection point in aview of the scene to the cursor as the cursor is moved.
 5. An apparatus,comprising: a display showing panning of contents of a scene responsiveto cursor motion using a speed upon detecting activation of a mousebutton, and where a pan rate of movement speed is set based on locationof the trigger relative to a model in a scene upon the activation, andwhere setting of the pan rate includes determining an intersection pointof a cursor with the model and fixing the intersection point in a viewof the scene to the cursor as the cursor is moved.